Structure for preventing shaft of constant velocity joint from coming off

ABSTRACT

The present invention presents a structure for preventing a shaft of constant velocity joint from coming off which allows changing design of connection between the shaft and an inner joint member to a type for disassembly or anti-disassembly. The anti-disassembly type is realized in such a manner that a wall at an opposite side to a shaft pulling out direction of a retaining ring groove of the shaft is used as a contacting part to a retaining ring, wherein at least two points are formed on the contacting part, one of which is on a perpendicular surface and the other is a corner of the contacting part, these two points are contacted with an inner surface of the retaining ring thereby provides the anti-disassembly type for preventing the ring from being contracted in a radial direction.

FIELD OF THE INVENTION

The present invention relates to a spline engagement structure forcoupling an inner joint member with a shaft of constant velocity jointsused in automobiles and various industrial equipments,.

BACKGROUND OF THE INVENTION

In conventional constant velocity joints for driving system or the likeof automobiles, an inner joint member and a shaft are engaged detachablywhile employing a structure for preventing the shaft from coming off forreduction of maintenance man-hours of replacement of boots or the like.With this structure, a groove is formed at end face of the shaft, aretaining ring is provided to this groove, and the shaft is engaged witha contacting face being formed on the inner joint member by means ofelastic expansion of the retaining ring. A mechanism used here is suchthat a corner is provided to a contacting face that interferes with theretaining ring when the shaft is pulled out, and disengagement isperformed by radially contracting the retaining ring by component forceof interference force with the retaining ring (see Japanese UnexaminedPatent Publication No. 08-68426, Japanese Utility Model Publication No.64-5124).

SUMMARY OF THE INVENTION

There is a demand for a structure for connecting a shaft and an innerjoint member that they should be anti-disassembly once built anddisassembly.

A structure according to Japanese Unexamined Patent Publication No.08-68426 is such that a retaining ring is provided at non-end face sideof a shaft and a groove for inserting a tool for contracting a retainingring is provided at end face of an inner joint member, thereby allowingassembly and disassembly. However, this mechanism requires much time andexpenses to machine the tool engagement groove on the inner jointmember.

Further, Japanese Utility Model Publication No. 64-5124 discloses astructure for contracting a retaining ring thereby allowing a shaft tobe pulled out. The publication, however, does not show how to manage anangle of a groove sidewall for effecting two types of configurationswhere the one allows a shaft to be pulled out and the other does not.

Considering the aforementioned problems, the present invention presentsa structure adapted to bring about two functions without increasinginside joint members, one of which prevents a shaft from coming off oncethe joint is assembled and the other allows a shaft to be pulled out.

The present invention provides a structure for preventing a shaft ofconstant velocity joint from coming off where the structure comprises aninner member of constant velocity joint having an insertion hole to beengaged with a shaft, a shaft having a ring-shaped retaining ringgroove, and a retaining ring located within said retaining ring groovethat can be elastically expanded and contracted. In the invention, whena pulling force is applied to the shaft, as the retaining ring isdisposed between a slope part formed in an insertion hole of the innerjoint member and the retaining groove, the shaft cannot be pulled outusually. The structure of the invention comprises at least twocontacting points in a sidewall of the retaining ring groove, which isopposite to the direction for pulling out the shaft.

Those contacting portions prevent the retaining ring to be contractedwhen a force is applied to the shaft in a pulling out direction becausesaid two contacting points contact the inner surface of the retainingring thereby preventing the contracting movement of the ring. Thus theshaft cannot be pulled out.

The present invention further comprises a step part on one side of theretaining ring groove that is opposite to the pulling out direction ofthe shaft. The step part has a depth shorter than the thickness of theretaining ring.

The shaft and the inner joint member are coupled with spline section.The shaft cannot be pulled out as the retaining ring and its groove arelocated outside the spline section of the inner joint member and theretaining ring is sandwiched by the at least two contacting points ofthe groove and the slope part of the insertion hole thereby preventinginward movement of the ring.

As the shaft is inserted to and coupled with the insertion hole of saidinner joint member through the spline section, the retaining ring grooveis located in the range of the spline section of the inner joint memberso that the retaining ring groove of the inner joint member forms aslope part to the retaining ring with facing to a retaining ring groovewall of the shaft.

With this configuration, even when a force is applied to the shaft in apulling out direction, the slope part formed in the spline section ofthe inner joint member, at least two contacting faces formed on a sidewall of the retaining ring groove at an opposite side of a shaft pullingout direction, or the step part contact with an inner surface of theretaining ring and sandwich the retaining ring thereby surely preventingmovement in a radial contracting direction.

With the present invention, when a force is applied to the shaft in apulling out direction, lower surface side of the retaining ring and atleast two contacting faces of the retaining ring groove, or the steppart make contact, and therefore, movement of the retaining ring in aradial contracting direction is prevented, and specification with whichdisassembly of the inner joint member and the shaft is not possible canbe produced simply.

Accordingly, it is possible to produce specification with whichdisassembly is possible by a structure of a side wall of a retainingring groove formed on a shaft without constituting an inner joint memberand a retaining ring each as exclusive member, and specification withwhich disassembly is not possible, and therefore, shared use of parts ismade possible thereby reducing man-hours required for parts control.

In order to obtain specification which allows disassembly of an innerjoint member and a shaft, with specification free from at least twocontacting faces on a side wall of a retaining ring groove of a shaft,and step part, by which such a force is given to move the retaining ringin a radial contracting direction using slope part at inner joint memberside as slope surface, when a force is applied to the shaft in a pullingout direction, diameter of the retaining ring is contracted, theretaining ring is moved in the insertion hole, and prevention by theretaining ring can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary sectional view of a constant velocity jointshowing embodiment of the present invention.

FIG. 2 is an enlarged view of part A in FIG. 1.

FIG. 3 is a perspective view of retaining ring shown in FIG. 1.

FIG. 4 is a sectional view showing a shaft pulled out statecorresponding to FIG. 2.

FIG. 5 is a sectional view showing a retaining ring corresponding toFIG. 2 in sandwiched state.

FIG. 6 is a sectional view showing one embodiment of a retaining ringgroove corresponding to FIG. 2.

FIG. 7 is a sectional view showing one embodiment of a retaining ringgroove corresponding to FIG. 2.

FIG. 8 is a sectional view showing a retaining ring groove correspondingto FIG. 2 in different position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1 to FIG. 8, embodiments of the present inventionwill be explained hereafter. For convenience of explanation, front edgeside denotes left side on the drawing and anti-front edge side denotesright side on the drawing. For convenience, explanations will be givenreferring to a fixed type constant velocity joint as shown in FIG. 1 inwhich the inner joint member is also referred to also as an inner ring.

As shown in FIG. 1, fixed type constant velocity joint 1 comprises outerring 2, inner joint member 3, torque transmission ball 4, and cage 5 fortorque transmission ball 4. Further, shaft 6 for transmitting torque ismounted to the inner joint member 3 in an engaging manner. The constantvelocity joint, not limited to the fixed type constant velocity joint 1,may be sliding movement type constant velocity joint such asdouble-offset type, cross-globe type, tripod type or the like.Meanwhile, inner joint member in the double-offset type and cross-globetype are also referred to as the inner ring, while inner joint member inthe tripod type are those referred to as a trunnion.

With the outer ring 2, a guide groove 7 in curved form is being formedon inside diameter surface in spherical form in circumferentialdirection at regular intervals. With the inner joint member 3, a guidegroove 8 in curved form is being formed on outside diameter surface inspherical form in circumferential direction at regular intervals. Thetorque transmission ball 4 is built into a ball track formed by theguide groove 7 of the outer ring 2 and the guide groove 8 of the innerjoint member 3.

As shown in FIG. 2, an insertion hole 9 for engagement with the shaft 6is formed on the inner joint member 3 in axial direction. A spline 10 isformed on inner circumference surface of insertion hole 9 and whenengaged with a spline 11 formed on the shaft 6, the inner joint member 3and the shaft 6 are transmittably coupled.

The front edge side of the shaft 6 of the insertion hole 9 is subjectedto diameter expansion processing and as shown in FIG. 2, a hole 12having diameter larger than the insertion hole 9 is being formed. Thehole 12 is continuous with a tapered part 10 a of termination of thespline 10 via a slope surface 12 a.

A retaining ring groove 13 in ring shape is being formed at front edgeside of the shaft 6. As shown in FIG. 2, depth L1 and width W1 of thisretaining ring groove 13 are made larger than wire diameter L2 of aretaining ring 14 for preventing a breakaway of the inner joint member 3and the shaft 6 (L1>L2, W1>L2). W1th this configuration, when insertingthe shaft 6 into the insertion hole 9 of the inner joint member 3 fromright to left on FIG. 4, it is possible to cause diameter contraction ofthe retaining ring 14 less than a minor diameter of the spline 10 of theinner joint member 3.

As shown in FIG. 3, although the retaining ring 14 has a ring shape, itis cut in part so that it may be inserted into the retaining ring groove13 after diameter contraction.

To a wall 13 a at front edge side of the retaining ring groove 13 (sidewall at an opposite side of a shaft pulling out direction) are formed awall 13 b perpendicular to an axis line to which an inner surface 14 aof the retaining ring 14 makes contact when a force is applied to theshaft 6 in a pulling out direction and an orthogonal step part 13 dwhich forms an corner 13 c. This step part 13 d has depth L3 in radialdirection of the shaft 6 and width W2 in axial direction both of whichare designed to be smaller than wire diameter L2 of the retaining ring14 (L2>L3, L2>W2). Namely, the step part 13 d is being formed by radialdirection dimension L3 that is smaller than wire diameter L2 of theretaining ring 13 and axial direction dimension W2 that is smaller thanthe same.

An inner surface of the retaining ring 14 denotes a center side surfacesince the retaining ring 14 is being formed in ring-shape, and a rangeshown by an arrow 14 a in FIG. 3 is meant. The range of this arrow 14 abecomes a half circle for circular section case and includes a boundarybetween lower surface and upper surface.

When L2≦L3, as the retaining ring 14 is accommodated within the steppart 13 d, a function for preventing the shaft from coming off is lost.Besides, when L2≦W2, width of the retaining ring 13 becomes larger andan idle space where the shaft 6 can move in right and left directions inFIG. 2 becomes large which is not practical.

As for attachment of the shaft 6 to the inner joint member 3, the shaft6 is inserted to the insertion hole 9 while the retaining ring 14 isdisposed to the retaining ring groove 13 and the retaining ring 14 isbeing diameter contracted. On this occasion, the retaining ring 14 movesin sliding state while making elastic contact with the spline 10 of theinsertion hole 9 (arrow A direction in FIG. 4).

When front edge of the shaft 6 reaches a position passing through theinsertion hole 9 (virtually, a position where contact with the spline 10is lost), an end 9 a at anti-front edge side of the insertion hole 9makes contact with a part 6 a of the shaft 6 and insertion is blocked.Alternatively, a retaining ring may be mounted separately to regulateinsertion length of the shaft 6 in which case the retaining ring makescontact with anti-front edge side of the insertion hole 9 therebypreventing further insertion.

At the point of time when insertion of the shaft 6 into the insertionhole 9 is ceased, the retaining ring 14 is positioned at the hole 12with larger diameter getting away from contact with the spline 10, andtherefore, diameter is expanded by elasticity. When the retaining ring14 is diameter expanded, an outer circumference surface of the retainingring 14 comes to contact with a peripheral wall of the hole 12 byelastic force, and therefore, the shaft 6 is brought into such that itis attached to the inner joint member 3.

At this state, the retaining ring 14 is not expanded completely and ispositioned within an engagement range of the spline 10, 11 while makingcontact with the peripheral wall of the hole 12 and tapered part 10 a.

Therefore, when a force (arrow B direction in FIG. 5) is applied to theshaft 6 in a pulling out direction, the shaft 6 moves in parallel fromFIG. 2 state to FIG. 5 state (this means movement in a direction ofdisengagement of spline 10, 11), while at this moment, a surfacepositioned at front edge side of the lower surface 14 a of the retainingring 14 makes contact with two points, the perpendicular wall 13 b ofthe step part 13 d and the corner 13 c, and at the same time, anti-frontedge side of the upper surface 14 b of the retaining ring 14 makescontact with either the tapered part 10 a formed at termination of thespline 10 of the inner joint member 3 or the slope part 12 a, and theretaining ring 14 is brought into sandwiched state.

A contact with the perpendicular wall 13 b takes place at a boundarybetween an inner surface 14 a and an upper surface 14 b of the retainingring 14. A contact with the corner 13 c takes place at a lower leftcircular arc surface, quarter area corresponding to from six o'clock tonine o'clock of a clock, in FIG. 5 of the lower surface 13 a of theretaining ring 13.

The perpendicular wall 13 b formed at front edge side of the retainingring groove 13 and the corner 13 c act as a contacting face of the shaftside and the tapered part 10 a at termination of the spline 10 or theslope part 12 a act as a slope part of the insertion hole 9 at innerjoint member 3 side.

When a force is applied to the perpendicular wall 13 b in a direction ofpulling out the retaining ring 14, an inward force is applied to theretaining ring by a slope part (tapered part 10 a or slope part 12 a) tourge the ring to be contracted in a direction toward the center of theshaft. However, the contraction movement of the ring is prevented by thecontacting part of the retaining ring groove 13, i.e., the perpendicularwall 13 c and the corner 13 c. Thus the retaining ring 14 cannot beentered in the retaining ring groove 13 as being locked. As a result,the shaft 6 cannot be pulled out.

In the case where the shaft 6 needs to be removed from the inner jointmember 3, the step part 13 d in the retaining ring groove 13 of theshaft 6 is not necessary. If the step part 13 d is not formed and aforce is applied to the shaft 6 in a pulling out direction, theretaining ring 14 is urged to be contracted by the tapered part 10 a andslope surface 12 a thereby entered into the retaining ring groove 13. Asa result, the shaft 6 can be removed in a direction opposite to arrow Ain FIG. 4.

As mentioned above, the step part 13 d is obvious at a glance as thestep 13 is formed in the retaining ring groove 13 of the shaft 6. Torender the shaft 6 removable, the step part 13 d in the retaining ringgroove 13 of the shaft 6 should be abolished. The appearance of theshaft provides a clear recognition if the shaft is removable or not.Further, common use of inner joint member can be accomplished in eachconstruction where the shaft is removable or anti removable, therebyreducing man-hours required for parts control.

When assembling the inner joint member 3 and the shaft 6, no specialstructure for preventing the removal of the shaft is needed and theconventional way of assembling can be simply used with contracting theretaining ring and inserting the same into the insertion hole of theinner joint member 3.

Besides, profile of the step part 13 d may not necessarily be formed bythe perpendicular wall 13 b and the corner 13 c as shown in FIG. 1. Forexample, a profile by the perpendicular wall 13 b and the corner 13 e asshown in FIG. 6 or by the perpendicular wall 13 b and the circular arcsurface 13 f as shown in FIG. 7 can also provide at least two contactingparts. Although this step part 13 d has been explained based on twocontacting parts in the embodiment, it is possible to increase thenumber of contacting parts depending on a profile of step part.

Furthermore, the retaining ring groove 13 may be located anywhere withina range of the insertion hole 9 of the inner joint member 3. Forexample, as shown in FIG. 8, a groove 15 is provided in the middle ofthe spline 10, this groove 15 and the retaining ring 13 are disposedopposedly so that a part of the retaining ring 14 can be introduced intothe groove 15. In this configuration, the structure of the retainingring groove 13 is the same as that in FIG. 2 and a slope part of theinner joint member 3 forms a wall 15 a at anti-front side of the groove15. If a wall 15 a is tilted so that the open side of the groove iswidened in similar fashion as the slope surface 12 a being continuouswith the tapered part 10 a of the spline 10, operational effects asattained in FIG. 2 are also obtained.

1. A structure for preventing a shaft of constant velocity joint fromcoming off comprising: an inner member of the constant velocity jointhaving an insertion hole for engagement with a shaft; a shaft having anannular retaining ring groove; and a retaining ring positioned in saidretaining ring groove and being radially expandable and contractibleelastically, wherein when a pulling out force is applied to the shaft,the shaft is prevented from coming out by the retaining ring disposedbetween a slope part formed in the insertion hole of the inner jointmember and said retaining ring groove, and wherein a sidewall of theretaining ring groove at an opposite side of a shaft pulling outdirection being formed with at least two contacting points contactingwith an inner surface of the retaining ring.
 2. A structure forpreventing a shaft of constant velocity joint from coming offcomprising: an inner member of the constant velocity joint having aninsertion hole for engagement with a shaft; a shaft having an annularretaining ring groove; and a retaining ring positioned in said retainingring groove and being radially expandable and contractible elastically,wherein when a pulling out force is applied to the shaft, the shaft isprevented from coming out by the retaining ring disposed between a slopepart formed in the insertion hole of the inner joint member and saidretaining ring groove,. and wherein a sidewall of the retaining ringgroove at an opposite side of the shaft pulling out direction beingformed with a step part originating from an outer surface of the shaftand having a radial dimension smaller than a diameter of wire of theretaining ring.
 3. The structure for preventing a shaft of constantvelocity joint from coming off according to claim 1, wherein theretaining ring groove is formed outside a range of the spline section ofthe inner joint member in an axial direction thereof where the shaft andthe inner joint member are coupled with the spline section and the shaftis attached to the insertion hole of said inner joint member.
 4. Thestructure for preventing a shaft of constant velocity joint from comingoff according to claim 2, wherein the retaining ring groove is formedoutside a range of the spline section of the inner joint member in anaxial direction thereof where the shaft and the inner joint member arecoupled with the spline section and the shaft is attached to theinsertion hole of said inner joint member.
 5. The structure forpreventing a shaft of constant velocity joint from coming off accordingto claim 1, wherein the retaining ring groove is formed within a rangeof the spline section of the inner joint member, the shaft and the innerjoint member are coupled with the spline section, the shaft is attachedto the insertion hole of said inner joint member, said retaining grooveis opposed to a groove formed in the spline section of the inner jointmember, and said slope part is formed on a wall of the groove at shaftpulling out side.
 6. The structure for preventing a shaft of constantvelocity joint from coming off according to claim 2, wherein theretaining ring groove is formed within a range of the spline section ofthe inner joint member, the shaft and the inner joint member are coupledwith the spline section, the shaft is attached to the insertion hole ofsaid inner joint member, said retaining groove is opposed to a grooveformed in the spline section of the inner joint member, and said slopepart is formed on a wall of the groove at shaft pulling out side.